Dummy pronoun
A dummy pronoun, also known as an expletive pronoun, is a pronoun that does not refer to anything, and exists only to satisfy a syntactic requirement. For example, in the sentence "It rained" the English pronoun "it" is generally analyzed as a dummy pronoun, inserted to fill the subject position, but not referring to anything.
The term 'dummy pronoun' refers to the function of a word in a particular sentence, not a property of individual words. For example, 'it' in the example from the previous paragraph is a dummy pronoun, but 'it' in the sentence "I bought a sandwich and ate it" is a referential pronoun (referring to the sandwich).
Unlike a regular pronoun, dummy pronouns cannot be replaced by any noun phrase.
Dummy pronouns are used in many languages across language families. Some of these families include Germanic languages, such as German and English, Celtic languages, such as Welsh and Irish, and Volta-Niger languages, such as Ewe and Esan. Other common languages with dummy pronouns include French and, colloquially, in Thai. Pronoun-dropping languages such as Spanish, Portuguese, Chinese, and Turkish do not require dummy pronouns.